A pebble is thrown up. It goes to a height and then comes back on the ground. State the different changes in form of energy during its motion.

When the pebble is thrown up with a velocity, its kinetic energy is maximum at the start of its journey and then it goes on decreasing. As the pebble moves upwards, its potential energy goes on increasing and then at the maximum height the potential energy is maximum, while kinetic energy is zero. It again starts to travel downwards under the action of gravity. Now, during its downward motion the potential energy slowly decreases and kinetic energy increases. Just before hitting the ground, the kinetic energy is maximum, while the potential energy is zero.